1. Field of the Invention
The present invention relates to a substrate processing apparatus and a method for manufacturing a semiconductor device and, more particularly, to those which monitor or control a warping amount of a substrate.
2. Description of the Related Art
Generally, in a sheet-type substrate processing apparatus, a substrate is processed while the substrate is forcedly sucked onto a substrate holding plate. In this case, when an adhesion of the substrate onto the substrate holding plate is not controlled, a problem is caused that a substrate characteristic of the substrate of the low adhesion is deteriorated seriously when it is transferred to a subsequent deposition process.
Specifically, as shown in FIG. 14, the sheet-type substrate processing apparatus performs processing such as deposition on the substrate by spraying a gas in a shower state from a gas dispersing plate 5 which is disposed above a substrate 1, while the substrate 1 is sucked and held on a substrate holding plate 2 which is heated by a resistance heater 3. A surface of the resistance heater 3 is kept at set temperature at all times.
It should be mentioned that, when warping amounts d1 and d2, which are space distances between the substrate 1 and the substrate holding plate 2 and show the adhesion, change, heat of the substrate holding plate 2, which is uniformly heated by the resistance heater 3 in the same state at all times, is not conducted to the substrate 1 uniformly, and the following disadvantages due to unevenness of a temperature distribution which depends on the warping amount d of the substrate (a generic name for d1 and d2) occur in a plane of the substrate.
Note that the warping amount of the substrate means a greatest value of a gap between a surface of the substrate holding plate 2 and a rear surface of the substrate 1, which is formed when the substrate 1 is deformed while the substrate 1 is held on the surface of the substrate holding plate 2 and a portion where the substrate 1 is not adhered to the substrate holding plate 2 is generated as a result.
As the distance d between the substrate 1 and the substrate holding plate 2 becomes longer, a heat transfer rate from the substrate holding plate 2 becomes worse, and temperature variations are generated in the in-plane temperature of the substrate depending on the distance d. Therefore, in the case of d1>d2, the temperature of the substrate near d2 is higher than the temperature of the substrate near d1.
According to the above technique of sucking and holding the substrate on the substrate holding plate, the entire surface of the substrate is not always sucked uniformly on the substrate holding plate. Since the process substrate undergoes a thermal treatment process including a plurality of deposition processes to be made into a targeted semiconductor substrate, a lamination number of deposition and heat history of the substrate increase as the processing proceeds, and as a result, it is possible that such a substrate easily has a plastic deformation amount of 100 μm or more warping amount d of the substrate, which is explained in FIG. 14.
When the adhesion of an end part of the substrate is not controlled, in other words, when the warping amount of the substrate during the processing is not controlled, the substrate characteristic after the processing receives a bad influence as a matter of course. This appears in, for example, deterioration in uniformity of a film thickness in thin film forming processing. Under present circumstances, there is no technique for controlling the warping amount of the substrate (that is, a nonuniform amount of temperature), and hence examining causes when a defect is caused in the substrate characteristic is troublesome. Therefore, there are demands for a technique for quantitatively controlling and monitoring these.
Incidentally, it is known that positions to measure temperature and a heating method for preventing generation of a slip in the substrate (wafer) are explained in the substrate heating technique disclosed in Japanese Patent Laid-Open No. Hei 6-260426. Although it explains that a contact area between the substrate and a substrate holding body (holder) cannot be controlled, the substrate is deformed and the contact area between the substrate and the substrate holding body changes in increasing the temperature, and therefore, an in-plane temperature difference is caused and the slip is generated in the substrate because of an influence of temperature of the outermost periphery of the substrate. Hence, the temperature is measured at a plurality of points which are positioned on the outer periphery part and on the points located 70% or higher of the radius apart from the center of the substrate, and heating of a heater is controlled so that a temperature difference between the respective temperature measuring points is 5° C. or lower. Thus, the heating treatment free from the generation of the slip without depending on uniformity of heating density of the heater and the contact area between the substrate and the substrate holding body is realized.
Moreover, as to control of a warp of the substrate by vacuum sucking, it is possible to control the warping amount of the substrate if a pressure difference is further increased and a sucking rate is increased, but it is difficult technically because the mechanism becomes complicated, Under the present circumstances, the warp is still generated even when the substrate is sucked with a large pressure difference of 300 to 500 Pa.
The present invention moves a step forward from that the temperature of the substrate changes according to a contact state between the substrate and the substrate holding body, and is made from the perspective that the temperature of the substrate holding body changes according to the contact state and there is a correlation between the temperature of the substrate holding body and the warping amount of the substrate.